2012/05/12 23:28:43 38.658 70.414 10.0 5.70 Tadjikistan
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2012/05/12 23:28:43:7 38.66 70.41 10.0 5.7 Tadjikistan
Stations used:
II.AAK II.NIL IU.KBL KR.KDJ KR.NRN
Filtering commands used:
hp c 0.015 n 3
lp c 0.033 n 3
Best Fitting Double Couple
Mo = 3.16e+24 dyne-cm
Mw = 5.60
Z = 25 km
Plane Strike Dip Rake
NP1 190 75 60
NP2 76 33 152
Principal Axes:
Axis Value Plunge Azimuth
T 3.16e+24 51 66
N 0.00e+00 29 198
P -3.16e+24 24 303
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.64e+23
Mxy 1.67e+24
Mxz -8.83e+21
Myy -8.06e+23
Myz 2.41e+24
Mzz 1.37e+24
----------####
-------------#########
---------------#############
---------------###############
----------------##################
--- -----------###################
---- P ----------#####################
----- ---------########### #########
-----------------########### T #########
------------------########### #########-
-----------------#######################--
-----------------#######################--
-----------------######################---
---------------######################---
#--------------####################-----
#-------------##################------
###----------################-------
#####-------#############---------
########--#######-------------
#########-------------------
#######---------------
###-----------
Global CMT Convention Moment Tensor:
R T P
1.37e+24 -8.83e+21 -2.41e+24
-8.83e+21 -5.64e+23 -1.67e+24
-2.41e+24 -1.67e+24 -8.06e+23
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20120512232843/index.html
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STK = 190
DIP = 75
RAKE = 60
MW = 5.60
HS = 25.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2012/05/12 23:28:43:7 38.66 70.41 10.0 5.7 Tadjikistan
Stations used:
II.AAK II.NIL IU.KBL KR.KDJ KR.NRN
Filtering commands used:
hp c 0.015 n 3
lp c 0.033 n 3
Best Fitting Double Couple
Mo = 3.16e+24 dyne-cm
Mw = 5.60
Z = 25 km
Plane Strike Dip Rake
NP1 190 75 60
NP2 76 33 152
Principal Axes:
Axis Value Plunge Azimuth
T 3.16e+24 51 66
N 0.00e+00 29 198
P -3.16e+24 24 303
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.64e+23
Mxy 1.67e+24
Mxz -8.83e+21
Myy -8.06e+23
Myz 2.41e+24
Mzz 1.37e+24
----------####
-------------#########
---------------#############
---------------###############
----------------##################
--- -----------###################
---- P ----------#####################
----- ---------########### #########
-----------------########### T #########
------------------########### #########-
-----------------#######################--
-----------------#######################--
-----------------######################---
---------------######################---
#--------------####################-----
#-------------##################------
###----------################-------
#####-------#############---------
########--#######-------------
#########-------------------
#######---------------
###-----------
Global CMT Convention Moment Tensor:
R T P
1.37e+24 -8.83e+21 -2.41e+24
-8.83e+21 -5.64e+23 -1.67e+24
-2.41e+24 -1.67e+24 -8.06e+23
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20120512232843/index.html
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The focal mechanism was determined using broadband seismic waveforms. The location of the event and the and stations used for the waveform inversion are shown in the next figure.
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The program wvfgrd96 was used with good traces observed at short distance to determine the focal mechanism, depth and seismic moment. This technique requires a high quality signal and well determined velocity model for the Green functions. To the extent that these are the quality data, this type of mechanism should be preferred over the radiation pattern technique which requires the separate step of defining the pressure and tension quadrants and the correct strike.
The observed and predicted traces are filtered using the following gsac commands:
hp c 0.015 n 3 lp c 0.033 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 1.0 265 75 -15 5.31 0.4343
WVFGRD96 2.0 265 70 -10 5.35 0.4434
WVFGRD96 3.0 265 50 0 5.41 0.4387
WVFGRD96 4.0 265 40 0 5.46 0.4367
WVFGRD96 5.0 265 35 0 5.49 0.4403
WVFGRD96 6.0 265 30 0 5.51 0.4477
WVFGRD96 7.0 265 25 -5 5.53 0.4569
WVFGRD96 8.0 260 20 -15 5.60 0.4668
WVFGRD96 9.0 250 15 -30 5.62 0.4858
WVFGRD96 10.0 240 15 -45 5.63 0.5048
WVFGRD96 11.0 195 80 80 5.62 0.5262
WVFGRD96 12.0 195 80 80 5.62 0.5445
WVFGRD96 13.0 195 80 80 5.61 0.5574
WVFGRD96 14.0 190 80 75 5.60 0.5726
WVFGRD96 15.0 190 80 75 5.60 0.5832
WVFGRD96 16.0 190 80 70 5.59 0.5935
WVFGRD96 17.0 190 80 70 5.59 0.6024
WVFGRD96 18.0 190 80 70 5.59 0.6095
WVFGRD96 19.0 195 75 70 5.60 0.6165
WVFGRD96 20.0 190 80 65 5.59 0.6212
WVFGRD96 21.0 190 75 65 5.60 0.6274
WVFGRD96 22.0 190 75 65 5.60 0.6309
WVFGRD96 23.0 190 75 60 5.60 0.6337
WVFGRD96 24.0 190 75 60 5.60 0.6371
WVFGRD96 25.0 190 75 60 5.60 0.6378
WVFGRD96 26.0 190 75 60 5.61 0.6372
WVFGRD96 27.0 190 75 60 5.61 0.6377
WVFGRD96 28.0 190 75 55 5.61 0.6357
WVFGRD96 29.0 190 75 55 5.61 0.6333
WVFGRD96 30.0 190 75 55 5.61 0.6316
WVFGRD96 31.0 185 75 50 5.61 0.6283
WVFGRD96 32.0 185 75 50 5.61 0.6256
WVFGRD96 33.0 185 75 50 5.62 0.6205
WVFGRD96 34.0 185 75 50 5.62 0.6154
WVFGRD96 35.0 185 75 50 5.62 0.6106
WVFGRD96 36.0 190 75 55 5.62 0.6045
WVFGRD96 37.0 190 75 55 5.62 0.5982
WVFGRD96 38.0 190 75 55 5.62 0.5920
WVFGRD96 39.0 190 75 55 5.62 0.5851
WVFGRD96 40.0 190 70 60 5.75 0.6044
WVFGRD96 41.0 190 70 60 5.76 0.5973
WVFGRD96 42.0 190 70 60 5.76 0.5898
WVFGRD96 43.0 190 70 60 5.76 0.5820
WVFGRD96 44.0 190 70 55 5.76 0.5743
WVFGRD96 45.0 190 70 55 5.77 0.5665
WVFGRD96 46.0 190 70 55 5.77 0.5586
WVFGRD96 47.0 190 70 55 5.77 0.5505
WVFGRD96 48.0 185 75 45 5.77 0.5424
WVFGRD96 49.0 185 75 45 5.77 0.5349
WVFGRD96 50.0 185 75 45 5.78 0.5273
WVFGRD96 51.0 185 75 45 5.78 0.5195
WVFGRD96 52.0 185 75 45 5.78 0.5117
WVFGRD96 53.0 185 75 45 5.79 0.5038
WVFGRD96 54.0 185 75 45 5.79 0.4959
WVFGRD96 55.0 185 75 45 5.79 0.4869
WVFGRD96 56.0 185 75 45 5.79 0.4790
WVFGRD96 57.0 185 75 40 5.80 0.4712
WVFGRD96 58.0 185 75 40 5.80 0.4636
WVFGRD96 59.0 185 75 40 5.80 0.4559
WVFGRD96 60.0 185 75 40 5.81 0.4482
WVFGRD96 61.0 185 75 40 5.81 0.4406
WVFGRD96 62.0 185 75 40 5.81 0.4330
WVFGRD96 63.0 185 75 40 5.81 0.4254
WVFGRD96 64.0 185 75 40 5.82 0.4179
WVFGRD96 65.0 185 75 40 5.82 0.4104
WVFGRD96 66.0 185 75 40 5.82 0.4019
WVFGRD96 67.0 185 75 40 5.82 0.3946
WVFGRD96 68.0 185 75 40 5.83 0.3873
WVFGRD96 69.0 185 75 40 5.83 0.3802
WVFGRD96 70.0 185 75 40 5.83 0.3730
WVFGRD96 71.0 185 75 40 5.83 0.3660
WVFGRD96 72.0 185 75 40 5.83 0.3590
WVFGRD96 73.0 185 75 40 5.84 0.3521
WVFGRD96 74.0 185 75 40 5.84 0.3453
WVFGRD96 75.0 185 75 40 5.84 0.3386
WVFGRD96 76.0 185 75 40 5.84 0.3320
WVFGRD96 77.0 185 75 40 5.84 0.3254
WVFGRD96 78.0 185 75 40 5.85 0.3189
WVFGRD96 79.0 185 75 40 5.85 0.3125
WVFGRD96 80.0 185 75 40 5.85 0.3061
WVFGRD96 81.0 185 75 45 5.85 0.2998
WVFGRD96 82.0 185 75 45 5.85 0.2937
WVFGRD96 83.0 185 75 45 5.85 0.2876
WVFGRD96 84.0 185 75 45 5.85 0.2816
WVFGRD96 85.0 185 75 45 5.86 0.2757
WVFGRD96 86.0 185 75 45 5.86 0.2699
WVFGRD96 87.0 185 75 45 5.86 0.2641
WVFGRD96 88.0 185 75 45 5.86 0.2585
WVFGRD96 89.0 185 75 45 5.86 0.2521
WVFGRD96 90.0 185 75 45 5.86 0.2466
WVFGRD96 91.0 185 75 45 5.86 0.2406
WVFGRD96 92.0 185 75 45 5.86 0.2352
WVFGRD96 93.0 185 75 45 5.87 0.2299
WVFGRD96 94.0 185 75 50 5.86 0.2247
WVFGRD96 95.0 185 75 50 5.87 0.2197
WVFGRD96 96.0 185 75 50 5.87 0.2147
WVFGRD96 97.0 185 75 50 5.87 0.2097
WVFGRD96 98.0 185 75 50 5.87 0.2048
WVFGRD96 99.0 185 75 50 5.87 0.2000
The best solution is
WVFGRD96 25.0 190 75 60 5.60 0.6378
The mechanism correspond to the best fit is
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The best fit as a function of depth is given in the following figure:
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The comparison of the observed and predicted waveforms is given in the next figure. The red traces are the observed and the blue are the predicted. Each observed-predicted component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number it the time shift required for maximum correlation between the observed and predicted traces. This time shift is required because the synthetics are not computed at exactly the same distance as the observed and because the velocity model used in the predictions may not be perfect. A positive time shift indicates that the prediction is too fast and should be delayed to match the observed trace (shift to the right in this figure). A negative value indicates that the prediction is too slow. The lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
hp c 0.015 n 3 lp c 0.033 n 3
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to thewavefroms. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. |
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
Should the national backbone of the USGS Advanced National Seismic System (ANSS) be implemented with an interstation separation of 300 km, it is very likely that an earthquake such as this would have been recorded at distances on the order of 100-200 km. This means that the closest station would have information on source depth and mechanism that was lacking here.
Dr. Harley Benz, USGS, provided the USGS USNSN digital data. The digital data used in this study were provided by Natural Resources Canada through their AUTODRM site http://www.seismo.nrcan.gc.ca/nwfa/autodrm/autodrm_req_e.php, and IRIS using their BUD interface.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureas of Mines, UC Berkely, Caltech, UC San Diego, Saint L ouis University, Universityof Memphis, Lamont Doehrty Earth Observatory, Boston College, the Iris stations and the Transportable Array of EarthScope.
The WUS used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
Model after 8 iterations
ISOTROPIC
KGS
FLAT EARTH
1-D
CONSTANT VELOCITY
LINE08
LINE09
LINE10
LINE11
H(KM) VP(KM/S) VS(KM/S) RHO(GM/CC) QP QS ETAP ETAS FREFP FREFS
1.9000 3.4065 2.0089 2.2150 0.302E-02 0.679E-02 0.00 0.00 1.00 1.00
6.1000 5.5445 3.2953 2.6089 0.349E-02 0.784E-02 0.00 0.00 1.00 1.00
13.0000 6.2708 3.7396 2.7812 0.212E-02 0.476E-02 0.00 0.00 1.00 1.00
19.0000 6.4075 3.7680 2.8223 0.111E-02 0.249E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.6200 3.2760 0.164E-10 0.370E-10 0.00 0.00 1.00 1.00
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Sat May 12 18:29:30 MDT 2012